Anti-HER2 mAb H2Mab-77 was established as previously described (29 (link)). To generate H77B, we subcloned VH cDNA of H2Mab-77 and CH of Dog IgGB into the pCAG-Ble vector (FUJIFILM Wako Pure Chemical Corporation). VL cDNA of H2Mab-77 and CL cDNA of dog kappa light chain were also subcloned into the pCAG-Neo vector (FUJIFILM Wako Pure Chemical Corporation). The vector of H77B was transduced into BINDS-09 (FUT8-deficient ExpiCHO-S) cells using the ExpiCHO Expression System (Thermo Fisher Scientific, Inc.) (37 (link)–41 (link)). H77Bf was purified using Ab-Capcher (ProteNova Co., Ltd.). Dog IgG was purchased from Jackson ImmunoResearch Laboratories, Inc.